Cyclopentadiene iron tricarbonyls



United States Patent 3 178 463 CYCLOPENTADIEllE lizon TRICARBONYLS Allen H. Filbey, Walled 'Lake, Mich., assignor to Ethyl Corporation, New York, N.Y., a corporation of Virginia N0 Drawing. Filed Apr. 11, 1963, Ser. No. 272,235

' Claims. (Cl. 260-439) a This invention relates to a new class of organometallic compounds and a process for their preparation. More specifically, this invention relates to the formation of compounds of iron, ruthenium and osmium in which three carbonyl groups and 'a compound containing the cyclopentadiene configuration are bonded to the metal atom.

This application is a continuation-in-part of forfeited application Serial No. 33,382, filed June 2, 1960.

An object of this invention is to provide organometallic compounds of iron, ruthenium and osmium in which a cyclopentadiene-type molecule and three carbonyl groups are bonded to the metal atom. Further objects will become apparent from a reading of the specification and claims which follow.

My compounds can be depicted by the empirical for- E mula in which CyH is a cyclopentadiene hydrocarbon and M is an iron subgroup metal, i.e., iron, ruthenium and osmium. Although CyH can be any cyclopentadiene hydrocarbon, CyH preferably contains from to about 14 carbon atoms. Typical of such cyclopentadiene hydrocarbons are cyclopentadiene, methylcyclopentadiene, propylcyclopentadiene, diethylcyclopentadiene, phenylcyclopentadiene, tert-butyl cyclopentadiene, p-ethylphenyl cyclopentadiene and the like. Although not bound by any theory, my novel compounds are believed to have the following structural configuration in which R R R R and R may be hydrogen or univalent hydrocarbon radicals preferably having less than about nine carbon atoms, said radicals preferably being selected from the class consisting of alkyl, aryl, alkaryl, aralkyl and cycloalkyl radicals. Each of the two double bonds in the cyclopentadiene molecule donates two electrons to the metal atom for bonding. This, with the additional six electrons donated by the three carbonyl groups, gives a total of donated electrons. As a result, the metal atom M (iron, ruthenium or osmium) attains the electron configuration of the next higher inert gas in the Periodic Table.

The exact nature of the substituent represented by R in the above formula is not critical as long as the substituent is not so bulky as to unduly hinder the reaction and is non-reactive under the conditions of the process employed. Besides the hydrocarbon substituents illustrated above, non-hydrocarbon substituents such as halogen, methoxy and the like are applicable.

Typical of the compounds of my invention are cyclopentadiene iron tricarbonyl, methylcyclopentadiene osmium tricarbonyl, propylcyclopentadiene ruthenium tricarbonyl, diethylcyclopentadiene iron tricarbonyl, p-ethylphenyl cyclopentadiene iron tricarbonyl and the like.

Of my novel compounds, the cyclopentadiene iron tricarbonyls are preferred since iron is a far more abundant --metal than either ruthenium-or osmium. Thus, these compounds may be made more cheaply than the corresponding ruthenium and osmium compounds.

My invention involves a process comprising reacting an iron subgroup metal carbonyl with a nickel compound of the type prepared by reacting nickel carbonyl with cyclopentadiene according to the process of Fischer et al., Chem. Ber., 92, 1423 (1957). Compounds of this type were originally believed to be bis(cyclopentadiene) nickels as proposed by Fischer et al., but are now believed by Fischer and others to be cyclopentadienyl nickel cyclopentenyls, Fischer et al., Tetrahedron letters, No. 1, p. 17 (1961); Dubeck et al., J. Am. Chem. Soc. 83, 1257 (1961). As a result of this process there is formed a cyclopentadiene metal tricarbonyl compound of iron, ruthenium or osmium.

The nickel compounds employed by reactants in my process are diamagnetic and contain two S-membered carbocyclic rings pi-bonded to a single nickel atom. A total of eight electrons are donated by the carbocyclic rings to the nickel atom such that that atom achieves the electronic configuration of the next higher inert gas, krypton. These reactants diifer markedly from bis(cyclopentadienyl) compounds of the type described in US. 2,680,758. Those compounds are paramagnetic and the nickel atom therein has'two electrons over and above those necessary for the nickel atom to achieve the electronic configuration of krypton. In other words, in the bis(cyclopentadienyl) compounds, the nickel atom has the electronic configuration of strontium since a total of 10 electrons are donated to the nickel atom by the'two cyclopentadienyl radicals.

In light of present knowledge, my invention comprises a process for the preparation of a cyclopentadiene iron subgroup metal tricarbonyl, said process comprising reacting a simple iron subgroup metal carbonyl with a cyclopentadienyl (cyclopentenyl) nickel wherein the cyclopentadienyl radical and the cyclopentenyl'radical each contain from 5 to about 14 carbon atoms. In other words, the process of this invention is a process for the preparation of a cyclopentadiene iron subgroup metal tricarbonyl which comprises reacting a simple iron subgroup metal carbonyl with a cyclopentadienyl (cyclopentenyl) nickel having the formula wherein R is selected from the class consisting of hydrogen and univalent hydrocarbon radicals having up to about nine carbon atoms, said radicals being preferably selected from the class consisting of alkyl, aryl, aralkyl, alkaryl and cycloalkyl radicals.

Nickel reactants wherein both carbocyclic rings have identical substituents are preferred since these compounds are more readily available. Typical reactants of this type are methylcyclopentadienyl (methylcyclopentenyl) nickel, propylcyclopentadienyl (propylcyclopentenyl) nickel, diethylcyclopentadienyl (diethylcyclopentenyl) nickel, p-ethylphenyl cyclopentadienyl (p-ethylphenylcyclopentenyl) nickel, and the like. a

The process of my invention comprises reacting a simple iron subgroup metal carbonyl with a nickel compound of the type described above. A simple metal carbonyl is a compound composed solely of metal atoms and carbonyl groups. Applicable simple metal carhonyls include iron pentacarbonyl, diiron enneacarbonyl, triiron dodecacarbonyl, ruthenium pentacarbonyl, diruthenium enneacarbonyl, triruthenium dodecacarbonyl, osmium pentacarbonyl and diosmium enneacarbonyl. The process comprises displacement of carbonyl groups from the iron subgroup carbonyl compound and formation of my novel cyclopentadiene iron subgroup metal tricarbonyl compounds.

The temperature at which my novel process may be conducted varies from about zero to about 80 C. The process may be carried out at normal pressures and is preferably conducted in an atmosphere of an inert gas such as nitrogen, argon, krypton, neon and the like. Further, my process can be conducted in an atmosphere of carbon monoxide. The use of the inert gas atmosphere or carbon monoxide is desirable since it prevents decomposition of the reactants or products and thereby increases the yield.

Agitation is preferably employed in conducting my process since its use insures an even reaction rate. Agitation can be accomplished in many ways such as, for example, by the use of an impeller which is immersed in the reaction mass, or by refluxing the reaction mixture.

The iron subgroup metal carbonyl reactant is customarily employed in excess since it is the cheaper of the two reactants. Preferably, the metal carbonyl reactant is employed in about 100 percent molar excess. The time required for reaction can vary greatly depending upon the other reaction conditions. Generally, however, the time varies from about 30 minutes to about 24 hours.

The process is preferably conducted in the presence of a non-reactive solvent. The nature of the solvent is not critical, however, and in the case where one of the reactants is a liquid, the liquid reactant may be used in sufficient excess to serve as the reaction solvent.

Typical of reaction solvents which may be employed in my process are high boiling saturated hydrocarbons such as n-octane, n-decane, and other paraifinic hydrocarbons having up to about 20 carbon atoms such as eicosane, pentadecane, and the like. Typical ether solvents are ethyloctyl ether, ethylhexyl ether, diethyleneglycol methyl ether, diethyleneglycol diethyl ether, diethyleneglycol dibutyl ether, ethyleneglycol dimethyl ether, ethyleneglycol diethyl ether, trioxane, tetrahydrofuran, ethyleneglycol dibutyl ether, and the like. Ester solvents which may be employed include pentyl butanoate, ethyl decanoate, ethyl hexanoate, and the like. Silicone oils such as the dimethyl polysiloxanes, bis(chlorophenyl) polysiloxanes, hexapropyldisilane, and diethyldipropyldiphenyldisilane may also be employed. Other ester solvents are those derived from succinic, maleic, glutaric, adipic, pimelic, suberic, azelaic, sebacic and pinic acids. Specific examples of such esters are di-(Z-ethylhexyl) adipate, di-(Z-ethylhexyl) azelate, di-(2-ethylhexyl) sebacate, di-(methylcyclohexyl) adipate, and the like. Of these enumerated solvents, those which are preferred for use in the process are the high boiling ethers and saturated aliphatic hydrocarbons. All of the above solvents will not be suitable for all of the specific embodiments of the invention since certain of the metal carbonyl reactants may be somewhat insoluble in some of the above solvents. Thus, care should be used in selecting the specific solvent for the specific reaction.

The particular solvent employed in any embodiment of the process should be selected from those solvents having the requisite boiling and/or freezing point. Frequently the boiling point of the solvent is used to control the reaction temperature when the process is carried out at atmospheric pressure. In such cases, the reaction mixture is heated at reflux, and the reflux temperature is determined by the boiling point of the solvent.

The ease of separating the product from the solvent depends on the degree of difference between the boiling and/or freezing points of the product and the solvent. If the product is a liquid having a boiling point close to that of the solvent, it is obvious that separation will be diflicult. In order to avoid this, it is preferable to select a solvent whose normal boiling point varies by at least 25 C. from the normal boiling point of a liquid product. If, on the other hand, the product is a solid, it is desirable that the freezing point of the solvent be at least 25 4 C. less than the temperature at which separation of the product is effected through crystallization. Obviously, if the solvent freezes before the solid product precipitates, it will be impossible to make a separation through crystallization.

The above criteria, as to physical properties of the solvent, are not unique to this process. In any chemical process, it is necessary to pick a solvent whose physical properties make it readily separable from the product being formed. It is deemed, therefore, within the skill of the art to select the most suitable solvent for use in any particular embodiment of my process.

In some cases, the process is advantageously carried out in the presence of an ultraviolet light source. This tends to decrease the reaction time and give a higher yield of product.

The reaction product may be separated from the reaction mass by such conventional means as chromatography, low temperature sublimation, low temperature distillation and recrystallization.

To further illustrate the scope of my novel process and the compounds produced thereby, there are presented the following examples in which all parts and percentages are by weight unless otherwise indicated.

Example I To a reaction vessel equipped with a thermometer, dropping funnel, magnetic stirrer and condenser with a nitro gen T was added about 88 parts of pure benzene and 6.5 parts of cyclopentadienyl (cyclopentenyl) nickel. To the red solution maintained at 25 C. under nitrogen was added 23 parts of iron pentacarbonyl. Two Dry Iceacetone traps, connected in series, were attached to the condenser nitrogen outlet, and the stirred solution was slowly brought to reflux. Initial gas evolution was observed as the reaction mixture refluxed at a temperature of 72 C. The gas solidified in the Dry Ice traps during the course of the reaction. After six hours at reflux, the temperature of the reaction mixture was 78 C., and very little gas evolution was observed. The reaction mixture was then allowed to cool somewhat, and nitrogen was then bubbled through the solution for about 15 minutes. The traps were immediately decontaminated with bromine in carbon tetrachloride; the resulting tetrachloride slurry was extracted with water, and the aqueous phase was analyzed to determine the nickel present as nickel bromide. A total of 24 percent of the original nickel was accounted for as nickel tetracarbonyl in this manner. The reaction mix-ture was then evaporated on an aspirator at 20 C., and the residue was triturated with low-boiling petroleum ether. A metallic mirror and purple crystals of dicyclopentadienyl diiron tetracarbonyl in the residue remained undissolved. The petroleum ether solution was then chromatographed through an alumina packed column. Elution with low-boiling petroleum ether yielded a yellow band which was collected, and the solvent was removed. Immediate sublimation of the residual oil onto a cold probe at full pump vacuum yielded 1.3 parts of yellow crystals having a melting point of 6 C. The infrared spectrum of the material in carbon tetrachloride showed a strong unsymmetrical doublet in the five micron region which is indicative of the presence of metallocarbonyl linkages. No bridging carbonyl absorption was observed. The infrared spectrum was very similar to that of butadiene iron tricarbonyl. The elemental analysis of the material established its identity as cyclopentadiene iron tricarbonyl. Calculated for C H O Fe: C, 46.7; H, 2.9; Fe, 27.1. Found: C, 46.5; H, 3.2; Fe 26.7 percent.

Example II One mole of methylcyclopentadienyl (methylcyclopentenyl) nickel and one mole of iron pentacarbonyl dissolved in toluene are agitated under nitrogen at 40 C. for eight hours. The reaction mixture is then discharged and solvent is removed by heating in vacuo. The residue is dissolved in low-boiling petroleum ether and chromatographed on alumina to yield methylcyclopentadiene iron t'ricar-bonyl.

Example III Example IV A solution comprising one mole of ethylphenyl cyclopentadienyl (ethylphenylcyclopentenyl) nickel and one mole of triruthenium dodecacarbonyl in diethyleneglycol dimethylether is heated to about 80 C. for 24 hours under nitrogen. The reaction product is discharged and heated in vacuo to remove the solvent. The residue is triturated with low-boiling petroleum ether and the triturates are chromatographed on alumina to yield ethylphenylcyclopentadiene iron tri'carbonyl. Similar results are obtained when ruthenium pentacarbonyl or diruthenium enneacarbonyl are substituted for triruthenium dodecacarbonyl in the above process.

Example V A diethyleneglycol solution containing one mole of phenylcyclopentadicnyl (phenylcyclopentenyl) nickel and two moles of diosmium enneacanbonyl is agitated under a carbon monoxide atmosphere for 24 hours at C. The reaction mixture is then discharged and solvent is removed by heating at reduced pressures. The residue is then subjected to. fractional sublimation to yield phenylcyclopentadiene osmium trioarbonyl. Similar results are obtained when osmium pentacarbonyl is substituted for diosmium enneacarbonyl in the above process. Phenylethylcyclopentadiene iron tricarbonyl is produced by reacting phenylethylcyclopentadienyl (phenylethylcyclopentenyl) nickel with iron pentacarbonyl. Cyclohexylcyclopentadiene iron tricarbonyl is prepared by reacting cyclohexylcyclopentadienyl (cyclohexylcyclopentenyl) nickel with iron pentacarbonyl.

My compounds are useful antiknocks when added to a petroleum hydrocarbon. They may be used as primary antiknock-s in which they are the major antiknock component in the fuel or as supplemental antiknocks. When used as supplemental antiknocks, they are present as the minor antiknock component in the fuel in addition to a primary antiknock such as a tetraalkyllead compound. Typical alkyllead compounds are tetraethyllead, tetrabutyllead, tetramethyllead, and various mixed lead' alkyls such as dimethyldiethyllead, diethyldibutyllead and the like. When used as either a supplemental or primary antiknock, my compounds may be present in the gasoline in combina tion with typical scavengers such as ethylene dichloride, ethylene dibromide, tricresylphosphate and the like.

My compounds are further useful in many metal platto' the tube 0.5 gram of cyclopentadiene iron tricarbonyl. The tube is heated at 400 C. for one hour after which time it is cooled and opened. The cloth has a uniform metallic grey appearance and exhibits a gain in weight of ing applications. In order to eifect metal plating using 7 my compounds, they are decomposed in an evacuated space containing the object to be plated. On decomposition, they lay down a film of metal on the object. The gaseous plating may be carried out in the presence of an inert gas so as to prevent oxidation of the plating metal or the object to be plated during the plating operation.

7 The gaseous plating technique finds wide application in forming coatings which are not only decorative but also protect the underlying substrate material.

Deposition of metal on a glass cloth illustrates the applied process. A glass cloth band weighing one gram is dried for one hour in an oven at 150 C. It is then placed in a tube which is devoid of air and there is added about 0.02 gram.

My compounds may also be employed as additives to residual and distillate fuels, e.g., jet fuels, home heater fuels and diesel fuels, to reduce smoke and/ or soot formation. 1

Having fully described my novel compounds, their mode of preparation and their many utilities, I desire to be limited only by the l-aw-ful'scope of the appended claims.

I claim:

1. A compound having the formula ia ntcola Flt in which R R R R and R are selected from the class consisting of hydrogen and univalent hydrocarbon radicals having less than about '9 carbon atoms, said radicals being selected from the class consisting of alkyl, alkaryl, aryl, aralkyl, and cycloalkyl radicals, M is an iron subgroup metal, and the total number of-carbon atoms present in R through R is less than about 9 carbon atoms.

2. Cyclopentadiene iron tricarbonyl.

3. Process for the preparation of a cyclopentadiene iron subgroup metal tricarbonyl, said process comprising reacting a simple iron subgroup metal carbonyl with a diamagnetic reactant having two five-membered carbocyclic rings bonded to a single nickel atom through a total of 8 electrons donated by the ring carbons in said carbocyclic rings to said nickel atom, such that said nickel atom has the electronic configuration of krpyton, each of said carbocyclic rings having from 5 to about 14 carbon atoms, the ring carbons in said rings being bonded to substituents which do not donate electrons to said nickel atom, said substituents being selected from the class consisting of hydrogen and univalent hydrocarbon radicals having less than about 9 carbon atoms, said hydrocarbon radicals being selected from the class consisting of alkyl, alkaryl, aryl, aralkyl, and cycloalkyl radicals.

4. Process for the preparation of a cyclopentadiene iron subgroup metal tricarbonyl, said process comprising reacting a simple iron subgroup metal carbonyl with a cyclopentadienyl (cyclopentenyl) nickel wherein the cyclopentadienyl radical and the cyclopentenyl radical each contain from 5 to about 14 carbon atoms, said cyclopentadienyl radical being selected from the class consisting of the cyclopentadienyl radical C H and hydrocarbon substituted cyclopentadienyl radicals having up to about 14 carbon atoms, said hydrocarbon substituted cyclopentadienyl radicals having substituents selected from the class consisting of hydrogen and univalent hydrocarbon radicals having less than about 9 carbon atoms, said radicals being selected from the class consisting of alkyl, alkaryl, aryl, aralkyl, and cycloalkyl radicals; said cyclopentenyl radical being selected from the class consisting of the cyclopentenyl radical C H and hydrocarbon substituted cyclopentenyl radicals having up to about 14 carbon atoms, said hydrocarbon substituted cyclopentenyl radicals having substituents selected from the class consisting of hydrogen, alkyl, alkaryl, aryl, aralkyl, and cycloalkyl radicals.

5. Process for the preparation of cyclopentadiene iron subgroup metal tricarbonyl, said process comprising re- 7 acting a simple iron carbonyl with a cyclopentadienyl (cyclopentenyl) nickel having the formula a a ,a, R

R R H wherein R is selected from the class consisting of hydrogen and univalent hydrocarbon radicals having up to about 9 carbon atoms, said radicals being selected from the class consising of alkyl, aryl, aralkyl, alkaryl, and

cycloalkyl radicals.

8 6. Process for the preparation of cyclopentadiene iron tricarbonyl, said process comprising reacting cyclopentadienyl (cyclopentenyl) nickel with iron pentacarbonyl.

References Cited by the Examiner Moeller: Inorganic Chemistry (1952), page 885.

Hallam et al.: J. Chemical Society (London), February 1958, pages 642-645.

T OBIAS E. LEVOW, Primary Examiner. 

1. A COMPOUND HAVING THE FORMULA 